With a diverse range of video source resolution in video display system, a scaling process for image interpolation is required before a video input signal is transferred into a flat-panel display device to display. A scaling unit for image interpolation upscaling or downscaling images of different formats and resolutions, so that the images can be supported by a display screen. As the size and resolution of the display panel increasing, image interpolation scaling technology plays a more important role in video processing system. Since the performance of image interpolation scaling technology directly affects the quality of displayed video, there is an urgent need to apply a high-quality image interpolation scaling technique in video display system, in order to improve visual experience of the user.
Nowadays, high definition (High Definition, HD) resolutions have been widely adopted in flat-panel display devices. Ultra-HD resolution 4K (3840*2160) has grown rapidly in this field. However, most video sources are still in a level of standard definition resolution due to limiting factors like filming, editing and processing devices. For example, when a video source with resolution of 480 P (720*480) is displayed on a 4K resolution display panel, the upscaling factor may reach 25, such a high magnification scaling results in that conventional image scaling technique based on bilinear and bicubic generates noticeable zigzag or distortion at edge regions of the image, and thereby cannot meet the actual demand of users.
Edge-directed adaptive image interpolation technique takes the difference among image content information into consideration, adaptively selects appropriate method to solve the distortion problem occurred in edges and particulars of the image. However, edge interpolation computation generally requires complicated algorithm computation and excessive computing resources, which is hard to be realized by using an integrated circuit design, and thus, it is difficult to meet the requirement of a video display system for real-time processing.